Internet videos generally have low frame rates, typically 15 Hz. Because the low frame rate, these video sources need motion estimation and motion compensation (MEMC) based frame rate conversion (FRC). Frame rate conversion is the process of converting from one frame rate to the other. Typically, this involves adding frames between existing frames to increase the frame rate, although it can involve dropping frames as well.
The low frame rate videos may result from several different frame rates such as 60 Hz, 30 Hz, 25 Hz and 24 Hz. This means that the dropping of frames to get to the resulting low frame rates may vary widely, leading to uneven dropping and incorrect time stamps. This makes motion vectors for an object uneven, regardless of whether the object velocity is constant. Some frames will have motion vectors that are higher than expected and others will have motion vectors lower than expected, or high-low motion. High low/motion degrades normal MEMC quality for several reasons. For example, the three-dimensional recursive motion vector calculation (MVC) method is less accurate because motion vectors calculated from previous frames are not the correct value for the current frame. Also, halo reduction logic is invalid because it compares motion vectors from the previous or future frames to current frame to detect cover and uncover areas. Another problem results from the output of the frame interpolation still containing high-low motion because the time between frames is uneven.
Therefore, it would be desirable to detect the cadence of low frame rate video and to use the detected cadence to correct the high-low motion in the motion vector calculations and frame interpolation portions of MEMC.